1. Field of the Invention
The field of the invention is a portable abrasive belt finishing machine having two supported active flights of a continuous abrasive belt mounted thereon. More specifically, the invention relates to an abrasive belt finishing machine which is portable and which has a fixed supported horizontal active flight and a fixed supported vertical active flight.
2. Description of the Prior Art
Heretofore it has been proposed to mount a continuous abrasive belt on three rollers to provide three flights of the belt with at least one flight being an active flight. Examples of abrasive belt finishing machines or sanders of this type are disclosed in the following U.S. patents.
______________________________________ PATENTEE U.S. PAT. NO. ______________________________________ Grover 2,470,615 Bedortha et al 2,976,652 Guinn 3,049,841 Dawson et al 3,110,989 Grover 3,429,077 Del Vecchio 3,534,508 ______________________________________
The Bedortha et al U.S. Pat. No. 2,976,652 discloses a belt sander having a downwardly facing unsupported horizontal active flight.
The Del Vecchio U.S. Pat. No. 3,534,508 discloses a downwardly facing active horizontal flight which is supported, i.e., which has a backup plate behind (above) the active flight.
The Dawson U.S. Pat. No. 3,110,989 discloses an upwardly extending active flight which has a backup plate therebehind.
The Guinn U.S. Pat. No. 3,049,841 discloses a portable handheld sander which has a downwardly facing unsupported horizontal active flight and a vertically extending active flight with a backup plate.
The Grover U.S. Pat. No. 2,470,615 and 3,429,077 disclose a right angle triangular arrangement of the axes of three rollers to provide three flights for a continuous abrasive belt mounted on the rollers with the hypotenuse flight being supported and being an active flight of the belt on the sander. The hypotenuse flight faces upwardly. This sander also provides an unsupported vertical flight on the short leg of the right angle triangle. In this sander, the framework mounting the triangularly arranged rollers can be rotated about the axis of one of the rollers to move the vertical flight to a downwardly facing horizontal flight position and the hypotenuse flight from an inclined angular position with respect to the horizontal through a horizontal position and then to another inclined position.
As will be described in greater detail hereinafter, the portable abrasive belt finishing machine of the present invention differs from the previously proposed abrasive belt finishing machines and sanders of the type disclosed in the patents referred to above by providing a portable machine which has a fixed active horizontal flight of the belt with a backup platen therebeneath and a fixed active vertical flight of the belt with a backup platen therebehind.